1. Field of the Invention
The invention relates generally to personal flotation devices and particularly to a personal flotation device incorporating a ballast member.
2. Description of the Prior Art
Heretofore, accidental immersion often resulted in death by two causes, aspiration leading to asphyxiation or hypothermia. A life saving system, to be viable for more than a few minutes, must successfully address both of these issues. Current life vests supply the requisite amount of buoyancy to return the victim to the surface, but often require a conscious victim's involvement to keep the airway clear. While it is common practice, as well as legally mandated, that all civilian, commercial, and non-civilian vessels carry Coast Guard approved life vests, many current water safety products provide only a limited portion of the safety they are capable of providing. They do provide for positive buoyancy during the shock of the initial entry into the water, but by incorporation of the concepts disclosed herein are capable of providing significantly improved airway protection after the initial insult with significantly increased reliability of airway protection and less bulk, cost and, consequently, more compliance.
By force of habit, life vests are currently designed after clothing and as such they open in the middle of the chest, producing a point of reduced buoyancy where it is least acceptable. The division of the forward chamber into two halves produces two side chambers which are each capable of generating righting moments in the water. When a righting moment is created on the body of an exhausted or unconscious individual, they can be stabilized in a face down or side down position. If the left or right side is out of the water, concurrent loss of muscle tone in the neck allows the face, nose, and mouth to be positioned underwater. Thus, current constructions of many life vest are really only adequate for conscious, alert, and active victims because they require participation, constant monitoring and adjustment by the user to keep the face and airway out of the water.
On sudden entry into the water, water on face actuates the Dive Reflex, which is a rapid uncontrollable inhalation. This reflex often results in aspirating water with its consequent choking and coughing. This distress further complicates the victim's ability to right themselves and assist in their own rescue. It is often the case that the sailor who is knocked overboard by the boom of the sail or is swept overboard by a wave, can suffer a temporary loss of consciousness. During this initial interval it is important that life vest not only buoy them to the surface, but that it also obtain and maintain the victim's face and airway out of the water until consciousness is regained.
The only life vest that is of any value is the life vest that is worn. Compliance can not be ignored as an important criteria in the design and manufacture of any safety product. The actual use of safety vests has begun to move forward by the hybrid personal flotation devices. The HPFD is a combination of a certain amount of inherently buoyant material along with an additional amount of inflatable buoyancy. Because of the reduced amount of bulk and therefore increased convenience associated with the hpfd, their acceptance is growing. U.S. Pat. No. 4,681,552 issued Jul. 21, 1987 to William Courtney, addresses the value of hybrid personal flotation devices. Like many vest style safety products and in particular all buoyancy compensators, the BC vest described in U.S. Pat. No. 4,681,552, when both chambers are inflated in the configuration disclosed in FIG. 1, would stabilize the user on their side, placing their airway underwater if the user was unable to hold their head up.
The vest that is constructed entirely from inflatable chambers is much more comfortable, convenient and therefore is frequently worn by itself and is now approved by the United States Coast Guard. The purely inflatable product such as the inflatable sailing harness, wind breaker, safety device, because of its compactness, is often the actual product worn by the victim. Many purely inflatable safety products attempt to compensate for the lack of inherent buoyancy by generating large amounts of lift. The use of excessive lift often results in the use of air under the arms where it creates the side up righting moment that can jeopardize the airway, a design defect addressed by the instant invention.
The airlines, because of their insoluble stowage problems are allowed the use of a purely inflatable device that has redundant chambers to guard against the failure problems inherent in single chamber safety devices. The scuba diver also wears a purely inflatable device known as a buoyancy compensator or “BC,” which looks like a traditional life vest but because it lacks at least reliability is not called such. The sailor is known to use inflatable wind breakers. All these devices, as well as many not described here, that are meant to provide surface flotation to individuals in the water, would be markedly improved by incorporation of the concepts described herein. Whether constructed solely from inherently buoyant means as are traditional life vests, or constructed from a hybrid composition of inherently buoyant and partially inflatable, or constructed from purely inflatable components, the specific location of a minimal amount of ballast in accordance with the construction herein disclosed would confer dramatic improvements in bulk, cost and compliance and consequently, in safety and survival statistics at sea.
The prior art on the use of dual chambered safety vests includes Swedish patent #203592 issued to Lindqvist on April 1966. This patent discloses a dual chambered product with a large forward chamber which would allow the victim to be stabilized in either a heads up position or if unconscious the victim could be stabilized lying over the forward float with their nose and mouth underwater. The device also relies on the victim's legs to apply tension to a draw string to pull the rear chamber up behind the victim's neck. For the active participant the product may have some utility but would be unsuccessful if not closely regulated. In addition the product is needlessly large and thus unnecessarily bulky when deflated, a feature that often results in the product being stored in a locker rather than being worn.
The buoyancy compensator is a convenience product that has unfortunately replaced the diver's safety vest. The buoyancy compensator is a specific adaptation of a purely inflatable safety product that is worn by the diver for use both at the surface and underwater. The product evolved from the orally inflated safety vest that had the appearance of and was often a horse collar vest. After decades of diving it was decided that the diver would benefit from the inclusion of a chamber to hold air while under water to offset the loss of buoyancy that occurs as the diver's thermal protective gear is compressed at depth. The initial compensators for this shift in buoyancy were containers that could be filled with air to displace water and therefore generate increased buoyancy as the diver's wet suit was compressed by the water. In an emergency this device could be easily disconnected from the diver.
The next step in the evolution of the buoyancy compensator was to use the air cylinder to inflate the safety vest, a product designed to protect the airway at the surface. Its proximity to the face and neck, its obstruction of the chest and therefore the site of controls for the dry suit diver, its general bulk and appearance left room for the advent of the life vest style buoyancy compensator. The initial detached, canister buoyancy compensators were of low volume and easy to ditch. The horse collar and then the life vest style buoyancy compensator became voluminous. The larger lift capacity became equivalent to the better the product. Buoyancy compensators are available with 80 lb. lift capacities. At the surface the high lift product conferred a sense of security because it would buoy the diver far above the water as long as diver remained in firm control of the product. As the diving population became more diverse in health and age, the false sense of security led to marked competitiveness over the amount of lift that could be attached to the diver. The product is so confused with security that a diver can not get onto a dive boat without wearing a high lift buoyancy compensator for “safety” reasons.
The inflatable products worn by scuba divers as disclosed in Greenwood's U.S. Pat. No. 3,436,777; Robert's U.S. Pat. No. 3,747,140; Walters' U.S. Pat. No. 4,016,616; Wright III's U.S. Pat. No. 4,137,585; Scott's U.S. Pat. No. 4,176,418; Maness's U.S. Pat. No. 4,324,234; or Courtney's U.S. Pat. No. 4,645,465 and 4,681,552, and all buoyancy compensators in the prior art are complicated by the attachment of an air cylinder that undergoes shifts in buoyancy throughout each dive as the cylinder empties and becomes more buoyant. The size of the shift in buoyancy is directly proportional to the size of the cylinder used. The nature of the shift in buoyancy, whether the cylinder ends up positively buoyant or only less negative, is a combination of cylinder composition, most commonly aluminum or steel and the water density, fresh, brackish or salt. Some air cylinders become six pounds positively buoyant when empty in sea water. This cylinder will float on its longitudinal axis as will the diver who is attached to that cylinder. Consequently, if for any reason the diver is unconscious, such as from a minor embolism from rapid ascent, blackout, trauma, medical problem or just over exhausted after being stranded at sea, they will eventually lie along side the air cylinder with their airway under the water and statistically the deaths are recorded as drowning. The current management of the life threatening side righting moments of every vest style buoyancy compensator is to disclaim liability for keeping the airway out of the water.
The instant invention discloses the integration of a very small amount of non-releasable weight exactly opposite the diver that converts the only inflatable worn by divers into a product that will protect the airway if the diver is unable to. The attachment of weight to the air cylinder in the prior art has been a way for carrying the ballast necessary for the diver to be able to submerge, and thus were designed to carry significant amounts of weight. Patents issued have turned on the design of the release system. The dive community demands that the attachment of significant amounts of weight must be able to be quickly released by one hand, by either hand. The release mechanism must be sure in that it must not accidentally release, but once the diver chooses to release the ballast the mechanism must be simple enough that it will not fail. All of the prior art by way of its incorporation of reliable release mechanism assures the diver that as an emergency is evolving and their weights are dropped to gain a better surface attitude, the air cylinder that was critical for use under water and is now empty will be attempting to float the diver on their side. If the diver is unable to oppose this action, their nose and mouth will be forcefully submerged.
It is to be noted that in U.S. Pat. No. 4,455,718, the quick release means is positioned centrally to allow access by either hand in the event of an emergency release. Prior to the release, the central positioning of the quick release mechanism necessitates that the weights as demonstrated in FIGS. 1 and 2 and be placed off center, potentially reenforcing the side righting moments of the life vest style buoyancy compensator. The keel retaining system disclosed is built into the buoyancy compensator so it will not be lost or left at home, the buoyancy compensator cannot be safely used without this critical component. In patent U.S. Pat. No. 3,670,509 it is noted that the ballast is located in front of the tank, close to the back of the diver and consequently closer to the axis of rotation which parallels the spine of the diver, thereby drastically reducing the rotational energy generated per unit of keel weight. This greatly reduces the effective strength of the angular rotation generated by a particular amount of ballast. Since some divers in the tropics may dive with only a few pounds of weight, it is important that the keel weight be kept as far away from the axis of rotation as is possible to maximize the strength of the righting moment. The critical location is on the exact opposite side of the tank from the diver. U.S. Pat. No. 3,670,509 refers to “substantial reducing” the tendency to force the diver face into the water. Use of the disclosed improvements will not allow the face to remain underwater. The ballast in patent U.S. Pat. No. 3,670,509 that attempts to reduce the face down righting moment, positions the diver so that they are able to “. . . activate the weight release mechanism.”, with the loss of the ballast the diver then would be back to floating on their side with their airway underwater. U.S. Pat. No. 3,967,459 locates the weight system inferior and adjacent to the diver nearly the exact opposite as disclosed herein. It is also noted that this weight system is intended to be released in an emergency reestablishing the tendency of the cylinder to submerge the diver's airway. The integrated ballast system of U.S. Pat. No. 4,752,263 is similar in that it is releasable, and located inferior and adjacent to the diver allowing for an airway endangering surface position. The ballast system disclosed in U.S. Pat. No. 2,120,420 places weight symmetrically about the diver which would totally eliminate any heads up righting moment and in fact would stabilize the diver 50% of the time in a face down position, additionally, this system is not designed to be used with an air cylinder, but rather a surface supply air system.
The instant invention achieves many critical features including providing that the weight be permanently attached, so that in an emergency it cannot be dropped. Since the keel weight must be small enough to not compromise surface safety, it must be located on the cylinder exactly opposite the diver where it generates the maximal rotational energy per pound of keel, rotational energy desperately needed to repeatedly turn the unconscious diver over onto their back against minor righting moments caused by limbs, variations in body density, and attached gear. In particular, if the victim dives near heavy surf where the waves can flip a victim over onto their face, a strong heads up righting moment is essential.
Another critical problem with the use of all current buoyancy compensators is that they combine high lift surface flotation needs with low lift underwater buoyancy needs. That same device at depth entraps pressurized air by design. The 190 lb. diver at 120 feet underwater requires nine pounds of air in their buoyancy compensator due to compression of their cold water wet suit, should that diver begin an uncontrolled ascent because; their regulator malfunctions, their tank is empty, they lose their mask and become disoriented, the power inflator sticks on their buoyancy compensators, they suffer a minor medical problems as they attempt an emergency assent, for whatever the reason, as the diver ascends, the air in their buoyancy compensator begins to expand. Ten pounds of air at 99 feet underwater, increases to 13.3 pounds at 66 feet and increases to twenty pounds at 33 feet and doubles forty pounds during the last 33 feet of the water column, enough air to create excessively fast ascent rates.
Recommended safe ascent rates are in the process of being reduced from 60 feet per minute to 20-30 feet per minute. A buoyancy compensator that can contain 30 lbs. of air can accelerate a diver who is stationary less than 10 feet underwater to the surface at average velocities over the last 4 feet, in excess of 200 to 250 feet per minute. Ascent rates from greater depths or ascent rates with larger buoyancy compensators such as currently available products generating 40, 60 or 80 lbs. of lift are unknown. It is known that if a person's lungs are fully inflated and they hold their breath while ascending three and a half (3½) or four (4) feet, their lungs will rupture. Pulmonary barotrauma introduces air into the circulation where it can obstruct circulation and result in infarction of the tissue involved. Since the diver is often vertical during an uncontrolled rapid ascent, the embolism most often travels to the brain. Unless the diver is re-compressed within minutes damage is permanent and possibly fatal. The prior art on buoyancy compensators, as is practiced in the diving community, unfortunately combines low lift buoyancy compensation needs with high lift surface flotation. The prior art buoyancy compensator is in desperate need of the many advances disclosed herein.
Once the conscious or unconscious individual is supported safely at the surface with their airway free and clear, the next major threat to the water borne victim whether recently returned from the depths or a survivor of a common carrier accident such as an airplane crash, is from; not being seen by search and rescue efforts, of being drowned while attempting a rescue or from hypothermia.
The rapid lowering of the body's core temperature results in interruption of life sustaining cognitive activities such as staying in a tucked fetal position, which further aggravates heat loss. With the loss of cognition the victim stops monitoring and responding to changing surface conditions. Inevitably hypothermia interferes in brain stem activities such as musculoskeletal tone and respiration. It is widely known that hypothermia is the actual killer in most accidental immersions. In response to such knowledge, exposure suits have been developed to insulate individuals and preserve core temperature thus extending survival from minutes to hours. An effective exposure suit is a large, bulky item that is prohibitively expensive. Despite these serious drawbacks it is the only alternative to dying from hypothermia within minutes and as such it is a legally mandated safety device for the industrial sector where its costs, bulk and inconveniences can be borne. Exposure suit costs and bulk have prevented their use being required in the recreational, civilian or commercial carrier sectors such as airlines, liners, ferries etc. Therefore it is clear that despite recognition that hypothermia is the active process in death at sea, there has not existed until this time a viable, affordable, storable means to control hypothermia.
To address this deficiency in the prior art, the current invention addresses both aspects of safety at sea. Rescue can rarely be performed within minutes. Often the sailor on watch is not missed until the next watch, obviously the single handed sailor is never missed. The sinking of a civilian or commercial carrier is often unattended for many hours or longer. As is noted in Harrigan's U.S. Pat. No. 2,114,301; Bennett's U.S. Pat. No. 3,105,981; or DeSimone's U.S. Pat. No. 4,187,570, there exists complex, bulky and costly means whereby jet pilots and navy personnel have personal power inflated life rafts. These automatically inflated life rafts require a cylinder whose cost alone is prohibitive to private and commercial carriers. The bulk of the cylinder, the bulk of the raft constructed from a fabric capable of withstanding pressurized inflation and high impact forces results in a device that is incompatible with civilian and commercial carriers such as airlines or ferries, yet alone individuals wind surfing, fishing from rubber rafts or touring ocean kayaks.